iPod nano stock shortages point to refresh?

A number of major U.S. retailers appear to be out of stock on certain models of the sixth-generation iPod nano, suggesting that Apple may be planning to refresh the device in the near future. 9to5Mac reports that Amazon is out of stock of roughly half its available nano configurations, Best Buy is similarly spotty in its availability, Walmart has only a few models in stock, and Target is likewise out of stock of several models. The report also indicates that Amazon.co.uk is also out of stock of several models; however, both the Apple Store and B&H Photo appear to be fully stocked. While the shortages could be due to some other cause, similar stock shortages have in the past correctly pointed to imminent refreshes or replacements for other Apple products.